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    Subject[PATCH 11/11] android: ram_console: honor dmesg_restrict
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    From: Nick Kralevich <nnk@google.com>

    The Linux kernel has a setting called dmesg_restrict. When true,
    only processes with CAP_SYSLOG can view the kernel dmesg logs. This
    helps prevent leaking of kernel information into user space.

    On Android, it's possible to bypass these restrictions by viewing
    /proc/last_kmsg.

    This change makes /proc/last_kmsg require the same permissions as
    dmesg.

    CC: Greg KH <gregkh@linuxfoundation.org>
    CC: Android Kernel Team <kernel-team@android.com>
    Signed-off-by: Nick Kralevich <nnk@google.com>
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    ---
    drivers/staging/android/ram_console.c | 3 +++
    1 files changed, 3 insertions(+), 0 deletions(-)

    diff --git a/drivers/staging/android/ram_console.c b/drivers/staging/android/ram_console.c
    index d956b84..b242be2 100644
    --- a/drivers/staging/android/ram_console.c
    +++ b/drivers/staging/android/ram_console.c
    @@ -99,6 +99,9 @@ static ssize_t ram_console_read_old(struct file *file, char __user *buf,
    char *str;
    int ret;

    + if (dmesg_restrict && !capable(CAP_SYSLOG))
    + return -EPERM;
    +
    /* Main last_kmsg log */
    if (pos < old_log_size) {
    count = min(len, (size_t)(old_log_size - pos));
    --
    1.7.3.2.146.gca209


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